Improvement in devices for teaching the metric system



W. F. BRADBURY.

DEVICES FOR TEACHING THE METRIC SYSTEM.

Patented May 2,1876.

LWUR/Lewes.

UNITED STATES PATENT GEEroE.

WILLIAM E: BaADBUErgoE CAMBRIDGE, MASSACHUSETTS.

IMPROVEMENT iN oEvIcEs FoR TEACHING THE M'ETRlc svsTEM.

Specification formingpart of Letters PatentNo'. 176,735, dated May 2, 1876; application tiled March 1, 1876.

. To all whom t may concern:

Be it known that I, WILLIAM lF. BRAD- BURY, of Cambridge, Middlesex county, Massachusetts, have invented a new and useful device for comparing the several tables of the metric system, which invention is fully set forth in the following speciticatiomrand represented in the accompanying drawing.

The object of my invention is to furnish a means ot' comparison of the various tables of weights and measures of` the metric system, which shall be obvious to the senses ot' sight and feeling; and it consists in the use of a liquid-measure, in cubical form, containing one liter, in combination with a cube oi' wood, or other suitable material, littingv and illing the same, and thus representing a cu- `bic decimeter, which is so yloadedor Vcompounded as to weigh one kilogram, the weight of `a liter ot' water. A

My invention also consists in said combination when one or more ot' the sides of such cube, one decimeter in length, are laid oft' in parallel lines at a distance of one centimeter from each otherrepreserrting long measure, or when these surfaces are further subdivided by crossing lines into square centimeters, representing square measure.

My invention also consists in making removable one or more ot' the cubic centimeters into vwhich the' said cube is supposed to be divided by intersecting planes through the surface-lines.

In the drawing, Figure 1 is an isometrical perspective ot' the liquid-measure. Fig. 2 is a similar view of the solidl cube with one cublc centimeter removed; and Fig. 3 is the removed cubic centimeter.

In this description of my invention I have chosen the liter and the corresponding cubic decimeter as the unit of measure, because of its greater convenience; but the same principle is involved in the use of a larger or smaller unit, and a cylindrical or other form may be given to these measures without departing from the spirit of my invention.

In the construction of my apparatus I form a cube of hard wood, or other material, having the specific gravity of water at a temperature of 390; or I so load or lighten the cube as to give to it that specific gravity, by fillingv l a central cavity with a heavier or lighter material, as the case may require, as shown in Fig. 2. Each side of the cube is a square decimeter. and these several faces are divided by ,crossing lines into one hundred square eeutimeters, which may be subdivided into milliinto hundredths are cut or engraved into the material, so as not to be effaced, and so as .to be perceptible to the touch.

by intersect-ing planes passing through the engravedlines into thousandths, each of which is a cubic centimeter; and the removal of one or more of the thousandths from the cube makesmore evident to the senses the relative proportions of the several measures. Suitamovable cube are desirable.

The literlmeasure, shown in Fig. l, forms a close-fitting case to receive and protect the other measures, Figs. 2 and 3.

Ten of the cubic centimeters may be detached together from the main cube, and their weight will be one decigram, or one hundred may be removed, weighing together one hectogram, if the uniform specilic gravity is equal to that of water at 390.

By means of my apparatus I am enabled to present, in tangible form, certain units off measure from each ofthe several tables named, susceptible of comparison with each other, viz: First, a measure of length'in decimeters, centimeters, and millimeters; second, a measure of surface in square decimeters, centimeters, and millimeters; third, a measure of solid contents in cubic deciineters, centimeters, and millimeters; fourth, a measureof dry or liquid measure in liters.

The relation existing between the measures of weight, capacity, and bulk become ,more apparent by the use of my apparatus, which of dry or liquid measures and a cubic decimeter of the table of cubic measures are of equal size or capacity, and that a kilogram in weight of a body having the specific gravit-y of water is, in bulk, equal to a cubic decime.- ter, and also equal to a liter; and that a cubic meters. The lines which divide the surfaces The cubic decimeter is supposed to be cut ble means of securing and releasing the reweights in grams, decigrams, hectograms, and A kilograms; fifth, a measure of capacity for' serves to demonstrate that a liter of the table centimeter of' a body having' the specific gravispaced vto designate certain ydecimal parts of ty of water Will weigh one gram, Snc. its bulk, substantially as here111 descr1bed.'

l claim as my invention- 3. A cubic decimeter, weighing one kilo- 1. The combination ofthe rectangular measgram, provided with a removable section repure for liquids with the cubical block repreresenting one or more cubic centimeters, senting or indicating the corresponding long, Weighing one or more grams ,substant1ally as square, and cubic measures, and the measure herein deSGIlbedv ot' weight, substantially as herein described. f

2. A measure for liquids, adapted to serve as a close-fitting case for a measure of solids, Witnesses: and in combination therewith, the'latter hav- A. H. SPENCER,

WM. F. BRADBURY.

ing the specific gravity of water, and suitably A. W. GATES. 

